Vehicle travel control apparatus

ABSTRACT

Provided is a vehicle travel control apparatus configured to set an operation mode of automatic start control to any one of a first mode, in which the automatic start control is executed, and a second mode, in which the automatic start control is not executed, the vehicle travel control apparatus being further configured to: issue to a driver a notification for inquiring whether the driver desires the automatic start control to be executed when the current travel state of an own vehicle is a specific state; and set the operation mode of the automatic start control to the first mode when the driver has performed a predetermined response operation in response to the notification.

CROSS-REFERENCES TO RELATED APPLICATION

The present application claims priority to Japanese patent applicationNo. JP 2019-046713 filed on Mar. 14, 2019, the content of which ishereby incorporated by reference in its entirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a vehicle travel control apparatusconfigured to execute following-travel inter-vehicle-distance control(or preceding-vehicle following-travel control).

2. Description of the Related Art

Hitherto, there has been proposed a vehicle travel control apparatusconfigured to execute following-travel inter-vehicle-distance control ofcausing a vehicle (own vehicle) to follow a preceding vehicle whilemaintaining an inter-vehicle distance between the own vehicle and thepreceding vehicle at a predetermined distance (see, for example,Japanese Patent Application Laid-open No. 2018-086874). In thefollowing, the above-mentioned control is also referred to as “adaptivecruise control”. In addition, the adaptive cruise control is hereinaftersimply referred to as “ACC”.

A related-art apparatus (first embodiment of Japanese Patent ApplicationLaid-open No. 2018-086874) is configured to execute automatic startcontrol of automatically starting the own vehicle when the precedingvehicle starts after the own vehicle has been stopped by the ACC inresponse to stopping of the preceding vehicle.

The related-art apparatus measures a stop time, which is a period oftime from when the own vehicle stopped in response to the stopping ofthe preceding vehicle to when the preceding vehicle starts. Therelated-art apparatus executes the automatic start control when the stoptime is within an automatic start permission time. Meanwhile, therelated-art apparatus releases (cancels) the automatic start controlwhen the stop time exceeds the automatic start permission time. In thiscase, the related-art apparatus starts the own vehicle after anoperation indicating an intention by the driver to start the vehicle isperformed.

The related-art apparatus always starts the own vehicle by the automaticstart control when the stop time is within the automatic startpermission time. However, as described below, depending on the travelstate of the own vehicle, the driver may or may not desire execution ofthe automatic start control.

For example, when the own vehicle is stopped on a general road in anurban area, the driver may not desire the automatic start control to beexecuted in consideration of a possibility that a pedestrian may enterahead of the own vehicle.

As another example, when the own vehicle is stopped on a limited-accessroad (limited highway), there is a high probability that thelimited-access road is congested. In such a situation, many drivers maydesire the automatic start control to be executed. However, some driversmay desire to start the own vehicle by their own driving operation.

SUMMARY

The present disclosure provides a vehicle travel control apparatuscapable of determining whether or not to execute automatic start controlin accordance with the desire of a driver by issuing an inquiry to thedriver about whether or not the driver desires the automatic startcontrol to be executed when it is determined that a travel state of anown vehicle is a state in which there is a high probability that thedriver desires the automatic start control to be executed.

According to one or more embodiments, there is provided a vehicle travelcontrol apparatus including: an information acquisition deviceconfigured to acquire vehicle peripheral information including objectinformation on an object existing around an own vehicle; a vehiclecontroller configured to execute, based on the vehicle peripheralinformation, following-travel inter-vehicle-distance control of causingthe own vehicle to follow a preceding vehicle traveling immediatelyahead of the own vehicle while maintaining an inter-vehicle distancebetween the own vehicle and the preceding vehicle at a predetermineddistance, and to execute automatic start control of causing the ownvehicle to automatically start when the preceding vehicle starts afterthe own vehicle has been stopped by the following-travelinter-vehicle-distance control in response to stopping of the precedingvehicle; a notification device configured to issue to a driver anotification for inquiring whether the driver desires the automaticstart control to be executed; and an operation device to be operated bythe driver in order to perform a predetermined response operation inresponse to the notification. The vehicle controller is configured toset an operation mode of the automatic start control to any one of afirst mode, in which the automatic start control is executed, and asecond mode, in which the automatic start control is inhibited frombeing executed. The vehicle controller is further configured to, whenthe own vehicle has stopped in response to the stopping of the precedingvehicle during execution of the following-travel inter-vehicle-distancecontrol and when the operation mode is set to the second mode,determine, based on the vehicle peripheral information, whether acurrent travel state of the own vehicle is a specific state, in whichthere is a high probability that the driver desires the automatic startcontrol to be executed, and cause the notification device to issue thenotification when it is determined that the travel state is the specificstate. The vehicle controller is further configured to set the operationmode to the first mode when the driver has performed the responseoperation, and set the operation mode to the second mode when the driverhas not performed the response operation.

Thus, the vehicle travel control apparatus is configured to determinewhether or not the current travel state of the own vehicle is thespecific state, in which there is a high probability that the driverdesires the automatic start control to be executed. When it isdetermined that the current travel state of the own vehicle is thespecific state, the vehicle travel control apparatus issues an inquiryto the driver about whether or not the driver desires the automaticstart control to be executed. Therefore, the vehicle travel controlapparatus can issue, in accordance with the current travel state of theown vehicle, an inquiry to the driver about whether or not the driverdesires the automatic start control to be executed.

Further, when the driver performs the response operation in response tothe inquiry, the vehicle travel control apparatus sets the operationmode of the automatic start control to the first mode. Therefore, whenthe preceding vehicle starts, the automatic start control is executed inresponse to the starting of the preceding vehicle. In contrast, when thedriver has not performed the response operation in response to theinquiry, the vehicle travel control apparatus sets the operation mode ofthe automatic start control to the second mode. Thus, the vehicle travelcontrol apparatus can determine whether or not to execute the automaticstart control in accordance with the desire of the driver by issuing theinquiry to the driver about whether or not the driver desires theautomatic start control to be executed.

In one or more embodiments, the vehicle controller is configured to,when the operation mode is set to the first mode: maintain the operationmode in the first mode until a predetermined finish condition issatisfied; and change the operation mode from the first mode to thesecond mode when the predetermined finish condition is satisfied.

According to this configuration, when the driver once performs theresponse operation in response to the inquiry (that is, when theoperation mode is set to the first mode), the operation mode of theautomatic start control is maintained in the first mode until the finishcondition is satisfied. Therefore, the automatic start control isexecuted each time the own vehicle stops in response to the stopping ofthe preceding vehicle until the finish condition is satisfied. Thedriver is not required to perform the response operation each time theown vehicle stops. Therefore, the convenience of the driver is improved.

In one or more embodiments, the information acquisition device isconfigured to further acquire, as the vehicle peripheral information,road information, which is information on a type of a road on which theown vehicle is traveling. Further, the vehicle controller is configuredto: determine, based on the vehicle peripheral information, whether afirst specific state condition, which is satisfied when the own vehicleis traveling on a limited-access road, is satisfied; and determine, whenit is determined that at least the first specific state condition issatisfied, that the travel state is the specific state.

In a case in which the own vehicle is stopped on a limited-access road,there is a high probability that the limited-access road is congested.In such a situation, the likelihood that the driver desires theautomatic start control to be executed is high. The vehicle controllercan determine such a situation to be the specific state, and issue aninquiry to the driver about execution of the automatic start control.

In one or more embodiments, the information acquisition device isconfigured to further acquire, as the vehicle peripheral information,road information, which is information on a type of a road on which theown vehicle is traveling. Further, the vehicle controller is configuredto: determine, based on the vehicle peripheral information, whether asecond specific state condition, which is satisfied when the own vehicleis traveling on a general road and a predetermined moving object doesnot exist around the own vehicle, is satisfied; and determine, when itis determined that at least the second specific state condition issatisfied, that the travel state is the specific state.

In a case in which the own vehicle is stopped on a general road, thedriver may not desire the automatic start control to be executed when apredetermined moving object (e.g., a pedestrian and/or a two-wheeledvehicle) exists around the vehicle. In contrast, when the predeterminedmoving object does not exist around the vehicle, there is a highpossibility that the driver desires the automatic start control to beexecuted. Therefore, the vehicle controller determines that the currenttravel state of the own vehicle is the specific state when the ownvehicle is traveling on a general road and the predetermined movingobject does not exist around the own vehicle. The vehicle controller canissue an inquiry to the driver about execution of the automatic startcontrol in a situation in which it is considered that the driver desiresthe automatic start control to be executed even when the own vehicle istraveling on a general road.

In one or more embodiments, the vehicle controller is configured to:determine, based on the vehicle peripheral information, whether atraffic-congestion condition, which is satisfied when the own vehicle istraveling in a traffic-congestion section, is satisfied; and determine,when it is determined that the traffic-congestion condition is satisfiedin addition to the first specific state condition or the second specificstate condition, that the travel state is the specific state.

It is considered that, when the own vehicle is traveling in atraffic-congestion section, there is a high likelihood that the driverdesires the automatic start control to be executed. In such a situation,the vehicle controller can issue an inquiry to the driver aboutexecution of the automatic start control.

According to one or more embodiments, the above-mentioned vehiclecontroller is implemented by a microprocessor programmed for performingone or more operations and/or functionality described herein. Inaddition, the vehicle controller may be implemented, in whole or inpart, by specifically configured to hardware (e.g., by one or moreapplication specific integrated circuits or ASIC(s)).

In the above description, in order to facilitate understanding of thepresent disclosure, names and/or reference symbols used in at least oneembodiment described later are enclosed in parentheses and are assignedto each of the constituent features corresponding to the at least oneembodiment. However, each of the constituent features is not limited tothe at least one embodiment defined by the reference symbols.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic configuration diagram of a vehicle travel controlapparatus according to at least one embodiment of the presentdisclosure.

FIG. 2 is a flowchart for illustrating a “first specific statedetermination routine” to be executed by a CPU of a driving support ECUillustrated in FIG. 1.

FIG. 3 is a flowchart for illustrating a “second specific statedetermination routine” to be executed by the CPU of the driving supportECU illustrated in FIG. 1.

FIG. 4 is a flowchart for illustrating an “automatic start controlexecution routine” to be executed by the CPU of the driving support ECUillustrated in FIG. 1.

DESCRIPTION OF THE EMBODIMENTS

Now, referring to the accompanying drawings, a description is given ofat least one embodiment.

<Configuration>

A vehicle travel control apparatus according to at least one embodiment(hereinafter sometimes simply referred to as “control apparatus”) isapplied to a vehicle. The vehicle to which the control apparatus isapplied is sometimes referred to as “own vehicle” so as to bedistinguished from other vehicles.

As illustrated in FIG. 1, the control apparatus includes a drivingsupport ECU (vehicle controller) 10, an engine ECU 20, a brake ECU 30, anavigation ECU 40, and a notification ECU 50. Those ECUs are electriccontrol units each including a microcomputer as a main part, and areconnected to one another so as to be able to mutually transmit andreceive information via a controller area network (CAN) (not shown).

The microcomputer herein includes a CPU, a ROM, a RAM, a readable andwritable nonvolatile memory, an interface I/F, and the like. Forexample, the driving support ECU 10 includes a CPU 101, a ROM 102, a RAM103, a nonvolatile memory 104, an interface 105, and the like. The CPUis configured to execute instructions (programs and routines) stored inthe ROM to implement various functions.

The driving support ECU 10 is connected to sensors (including switches)listed below, and is configured to receive detection signals or outputsignals from those sensors. Alternatively, each sensor may be connectedto an ECU other than the driving support ECU 10. In this case, thedriving support ECU 10 receives the detection signal or the outputsignal of the sensor from the ECU to which the sensor is connected viathe CAN.

An accelerator pedal operation amount sensor 11 is configured to detectan operation amount (accelerator opening degree) of an accelerator pedal11 a, and output a signal representing an accelerator pedal operationamount AP.

A brake pedal operation amount sensor 12 is configured to detect anoperation amount of a brake pedal 12 a, and output a signal representinga brake pedal operation amount BP.

A vehicle speed sensor 13 is configured to detect a travel speed(vehicle speed) of the vehicle, and output a signal representing avehicle speed SPD.

An ambient sensor 14 is configured to acquire information on a roadaround the vehicle (e.g., a travel lane along which the vehicle istraveling and an adjacent lane adjacent to the travel lane) andinformation on three-dimensional (3D) objects existing on the road. The3D object means a moving object, for example, a motor vehicle, apedestrian, and a bicycle, or a fixed object, for example, a guard railand a fence. Those 3D objects are hereinafter also referred to as“objects”. The ambient sensor 14 includes a radar sensor 14 a and acamera sensor 14 b.

The radar sensor 14 a is configured to radiate, for example, a radiowave in a millimeter wave band (hereinafter referred to as “millimeterwave”) to a peripheral region of the vehicle, and to receive amillimeter wave (namely, a reflected wave) reflected by an objectexisting in the radiation range. The peripheral region of the vehicleincludes at least a region directly in front of the vehicle, a region inthe front-right direction of the vehicle, and a region in the front-leftdirection of the vehicle. Further, the radar sensor 14 a is configuredto determine whether or not an object exists by using a relationshipbetween the transmitted millimeter wave and the received reflected wave,and calculate “information on the relative relationship between thevehicle and the object” to output a determination result and acalculation result. The information on the relative relationship betweenthe vehicle and the object includes a distance between the vehicle andthe object, an orientation (or position) of the object with respect tothe vehicle, a relative speed between the vehicle and the object, andother such information.

More specifically, the radar sensor 14 a includes a millimeter wavetransmission/reception device and a signal processing device. The signalprocessing device obtains, each time a predetermined period elapses, theinformation on the relative relationship between the vehicle and theobject based on a phase difference between the millimeter wavetransmitted from the millimeter wave transmission/reception device and areflected wave received by the millimeter wave transmission/receptiondevice, an attenuation level of the reflected wave, a period of timefrom the transmission of the millimeter wave to the reception of thereflected wave, and other such information. The information includes, asdescribed below, “longitudinal distance Dfx(n), relative speed Vfx(n),lateral distance Dfy(n), relative lateral speed Vfy(n), and other suchinformation” with respect to each detected object(n).

The longitudinal distance Dfx(n) is the distance between the own vehicleand an object(n) (e.g., a preceding vehicle) along a center axis (anaxis extending in a front-rear direction) of the own vehicle. When theobject(n) is a preceding vehicle, the longitudinal distance Dfx(n) isthe inter-vehicle distance between the own vehicle and the precedingvehicle.

The relative speed Vfx(n) is a difference (=Vs-SPD) between a speed Vsof the object(n) (e.g., the preceding vehicle) and the vehicle speed SPDof the own vehicle. The speed Vs of the object(n) is a speed of theobject(n) in a travel direction of the own vehicle.

The lateral distance Dfy(n) is a distance of a “center position of theobject(n) (e.g., a center position of a vehicle width of the precedingvehicle)” from the center axis of the own vehicle in a directionorthogonal to the center axis.

The relative lateral speed Vfy(n) is a speed of the center position ofthe object(n) (e.g., the center position of the vehicle width of thepreceding vehicle) in the direction orthogonal to the center axis of theown vehicle.

The camera sensor 14 b includes a camera and an image processor. Thecamera is a monocular camera or a stereo camera. The camera takes imagesof scenes forward of the vehicle to acquire image data each time apredetermined period elapses. The image processor is configured todetermine whether or not an object exists based on the taken image data,and calculate information on the relative relationship between thevehicle and the object to output a determination result and acalculation result.

The driving support ECU 10 is configured to combine the “information onthe relative relationship between the vehicle and the object” obtainedby the radar sensor 14 a and the “information on the relativerelationship between the vehicle and the object” obtained by the camerasensor 14 b with each other, to thereby determine “information on therelative relationship between the vehicle and the object” each time apredetermined period elapses.

Further, the camera sensor 14 b is configured to identify (determine)the type of the detected object based on the image data. Examples oftypes of objects include four-wheeled vehicles, two-wheeled vehicles,and pedestrians. The image processor stores data obtained by patterningan object such as a four-wheeled vehicle, a two-wheeled vehicle, or apedestrian in a memory in advance. The image processor in this exampleidentifies whether the object corresponds to a four-wheeled vehicle, atwo-wheeled vehicle, or a pedestrian by performing pattern matching onthe image data.

The information on the object acquired by the ambient sensor 14(including the information on the relative relationship between thevehicle and the object, and the type of the object) is referred to as“object information”. The ambient sensor 14 repeatedly transmits theobject information to the driving support ECU 10 each time apredetermined time elapses.

The engine ECU 20 is connected to an engine actuator 21. The engineactuator 21 includes a throttle valve actuator configured to change anopening degree of a throttle valve of an internal combustion engine 22.The engine ECU 20 can drive the engine actuator 21 to change a torquegenerated by the internal combustion engine 22. The torque generated bythe internal combustion engine 22 is transmitted to drive wheels (notshown) via a transmission (not shown). Thus, the engine ECU 20 cancontrol the engine actuator 21 to control a driving force of thevehicle, to thereby change an acceleration state (acceleration).

When the vehicle is a hybrid vehicle, the engine ECU 20 can control adriving force of the vehicle generated by any one of or both of“internal combustion engine and electric motor” serving as vehicledriving sources. When the vehicle is an electric vehicle, the engine ECU20 can control a driving force of the vehicle generated by an electricmotor serving as a vehicle driving source.

The brake ECU 30 is connected to a brake actuator 31. The brake actuator31 is provided in a hydraulic circuit (not shown) between a mastercylinder configured to pressurize a working fluid with a stepping forceon a brake pedal 12 a and friction brake mechanisms 32 provided on thefront/rear left/right wheels. The brake actuator 31 adjusts a hydraulicpressure of the working fluid to be supplied to a wheel cylinderintegrated into a brake caliper 32 b of the friction brake mechanism 32in accordance with an instruction from the brake ECU 30. With the wheelcylinder being operated by the hydraulic pressure, a brake pad ispressed against a brake disc 32 a to generate a friction braking force.Thus, the brake ECU 30 can control the brake actuator 31 to control thebraking force of the vehicle and change an acceleration state (adeceleration, namely, a negative acceleration) of the vehicle.

The navigation ECU 40 includes a GPS receiver 41 configured to receive aGPS signal for detecting the “latitude and longitude” of the place atwhich the vehicle is positioned, a map database (DB) 42 configured tostore map information, a touch panel 43, and a communication device 44.

The map information stored in the map DB 42 includes road information.The road information includes road parameters for each road section. Forexample, in the road information, a road type, a road width, a roadcurvature, a road gradient, and the like are associated with each roadsection. In this example, the road type is any one of a limited-accessroad (highway) and a general road. The navigation ECU 40 repeatedlytransmits the road information on the road on which the vehicle istraveling to the driving support ECU 10 each time a predetermined timeelapses.

The touch panel 43 is a touch panel type display, and can display a map,an image, and the like. The navigation ECU 40 performs variousarithmetic processes based on the latitude and longitude of the place atwhich the vehicle is positioned, the map information, and the like, anddisplays on the touch panel 43 the position of the vehicle on the map.

The communication device 44 is configured to communicate to and from aninformation center (information providing facility). For example, thecommunication device 44 receives road traffic information from theVehicle Information and Communication System (VICS) (trademark). Theroad traffic information includes, for example, information on atraffic-congestion section and information on a closed road section.

The notification ECU 50 is connected to a display 51 and a speaker 52.The display 51 is a multi-information display arranged in front of thedriver's seat. The display 51 is configured to display various types ofinformation in addition to display of measurement values such as thevehicle speed SPD and the engine rotation speed. A head-up display maybe employed as the display 51. When the speaker 52 receives a soundcommand from the driving support ECU 10 via the notification ECU 50, thespeaker 52 generates a sound corresponding to the sound command. The“display 51 and speaker 52” may be collectively referred to as a“notification device”.

A steering wheel (not shown) of the vehicle includes an operation device60 for performing an operation relating to ACC. The operation device 60is arranged at a position facing the driver and operable by the driver.The operation device 60 includes a main switch 61, a cancel switch 62,an inter-vehicle time setting switch 63, a resume/acceleration switch64, a set/deceleration switch 65, and an automatic start switch 66.Details of the method of operating those switches 61 to 66 are describedlater.

(Overview of ACC)

The driving support ECU 10 can execute the ACC. The ACC itself is widelyknown (see, for example, Japanese Patent Application Laid-open No.2014-148293, Japanese Patent Application Laid-open No. 2006-315491,Japanese Patent No. 4172434, and Japanese Patent No. 4929777). Inaddition, the ACC may be also referred to as “following-travelinter-vehicle-distance control (or preceding-vehicle following-travelcontrol)”.

The ACC includes two types of control, namely, following-travel-modecontrol and constant-speed-travel-mode control. Thefollowing-travel-mode control is control of causing the own vehicle tofollow a preceding vehicle traveling immediately ahead of the ownvehicle while maintaining an inter-vehicle distance between the ownvehicle and the preceding vehicle at a predetermined distance, withoutrequiring operation of the accelerator pedal 11 a and the brake pedal 12a. The constant-speed-travel-mode control is control of causing thevehicle to travel such that the travel speed of the vehicle matches atarget speed (set speed Vset) without requiring operation of theaccelerator pedal 11 a and the brake pedal 12 a.

In the following description (routines of FIG. 2 to FIG. 4), it isassumed that the control apparatus is executing thefollowing-travel-mode control. Therefore, the following-travel-modecontrol is mainly described.

When the ACC is started (when the main switch 61 is turned on asdescribed later), the driving support ECU 10 determines, based on theobject information acquired by the ambient sensor 14, whether or notthere is a vehicle (that is, a following target vehicle) traveling ahead(immediately ahead) of the own vehicle and that is to be followed by theown vehicle. For example, the driving support ECU 10 determines whetheror not the relative position of the object(n) identified from thelateral distance Dfy(n) and longitudinal distance Dfx(n) of the detectedobject(n) exists in a following-target-vehicle area determined inadvance. The following-target-vehicle area is an area defined in advanceso that an absolute value of a distance in a lateral direction withrespect to the travel direction of the own vehicle decreases as adistance in the travel direction increases.

The driving support ECU 10 selects the object(n) as the following targetvehicle (a) when the object(n) exists in the following-target-vehiclearea for a predetermined period or longer. Then, the driving support ECU10 executes the following-travel-mode control. When there are aplurality of objects for which the relative position exists in thefollowing-target-vehicle area for the predetermined period or longer,the driving support ECU 10 selects an object having the shortestlongitudinal distance (inter-vehicle distance) Dfx(n) from among thoseobjects as the following target vehicle (a).

The driving support ECU 10 calculates a target acceleration Gtgt inaccordance with any one of Expression (1) and Expression (2) givenbelow. In Expression (1) and Expression (2), Vfx(a) represents arelative speed of the following target vehicle (a), k1 and k2 representpredetermined positive gains (coefficients), and ΔD1 represents aninter-vehicle distance difference (=Dfx(a)−Dtgt) obtained by subtractinga “target inter-vehicle distance Dtgt” from a “longitudinal distance(inter-vehicle distance) Dfx(a) of the following target vehicle (a)”.The target inter-vehicle distance Dtgt is calculated by multiplying atarget inter-vehicle period Ttgt set by using the inter-vehicle timesetting switch 63 by the vehicle speed SPD of the own vehicle (that is,Dtgt=Ttgt·SPD). However, when the vehicle speed SPD of the own vehicleis equal to or less than a predetermined vehicle speed (low vehiclespeed) threshold value SPDLth, the target inter-vehicle distance Dtgt isset to a constant distance Dp determined in advance.

The driving support ECU 10 uses Expression (1) given below to determinethe target acceleration Gtgt when the value (k1·ΔD1+k2·Vfx(a)) ispositive or “0”. The value ka1 represents a positive gain (coefficient)for acceleration, and is set to a value equal to or smaller than “1”.

The driving support ECU 10 uses Expression (2) given below to determinethe target acceleration Gtgt when the value (k1·ΔD1+k2·Vfx(a)) isnegative. The value kd1 represents a positive gain (coefficient) fordeceleration, and is set to “1” in this example.

Gtgt(for acceleration)=ka1·(k1·ΔD1+k2·Vfx(a))  (1)

Gtgt(for deceleration)=kd1·(k1·ΔD1+k2·Vfx(a))  (2)

The driving support ECU 10 uses the engine ECU 20 to control the engineactuator 21 to control the driving force of the vehicle, and, asrequired, uses the brake ECU 30 to control the brake actuator 31 tocontrol the braking force of the vehicle so that the acceleration of thevehicle matches the target acceleration Gtgt.

The driving support ECU 10 can also execute the automatic start controlduring execution of the following-travel-mode control. The automaticstart control is control of causing the own vehicle to automaticallystart without requiring a predetermined operation (any one of operation1 and operation 2 described later) by the driver when the followingtarget vehicle (a) starts after the own vehicle has stopped in responseto the following target vehicle (a) having stopped.

The driving support ECU 10 sets the operation mode of the automaticstart control to any one of an ON mode (first mode), in which theautomatic start control is executed, and an OFF mode (second mode), inwhich the automatic start control is not executed.

In a case in which the driving support ECU 10 is executing thefollowing-travel-mode control, when the following target vehicle (a)stops, the driving support ECU 10 causes the own vehicle to stop inresponse to the stopping of the following target vehicle (a). It isassumed that the operation mode of the automatic start control is in theON mode in a situation in which the own vehicle is stopped immediatelybehind the following target vehicle (a). In this case, when thefollowing target vehicle (a) starts, the driving support ECU 10 executesthe automatic start control. Then, the driving support ECU 10 continuesthe following-travel-mode control.

Next, it is assumed that the operation mode of the automatic startcontrol is in the OFF mode in a situation in which the own vehicle isstopped immediately behind the following target vehicle (a). In thiscase, when the following target vehicle (a) starts, the driving supportECU 10 maintains the own vehicle in a stopped state without executingthe automatic start control. When the driver performs a predeterminedoperation in a situation in which the own vehicle is thus maintained tobe stopped, the driving support ECU 10 starts the vehicle. Then, thedriving support ECU 10 continues the following-travel-mode control. Thepredetermined operation is any one of the following operation 1 andoperation 2.

(Operation 1) The driver presses the resume switch 64.

(Operation 2) The driver steps on the accelerator pedal 11 a (that is,the accelerator pedal operation amount AP changes from “0” to a “valuegreater than 0”).

The driving support ECU 10 determines that there is no following targetvehicle when an object(n) does not exist in the following-target-vehiclearea. In this case, the driving support ECU 10 executes theconstant-speed-travel-mode control. Specifically, the driving supportECU 10 determines the target acceleration Gtgt based on the set speedVset and the vehicle speed SPD such that the vehicle speed SPD of thevehicle matches the set speed Vset. The driving support ECU 10 sets thetarget acceleration Gtgt to “0” when the set speed Vset matches thevehicle speed SPD. When the set speed Vset is higher than the vehiclespeed SPD, the driving support ECU 10 increases the target accelerationGtgt. When the set speed Vset is lower than the vehicle speed SPD, thedriving support ECU 10 decreases the target acceleration Gtgt. Thedriving support ECU 10 controls the engine actuator 21 by using theengine ECU 20 to control the driving force of the vehicle, and controlsthe brake actuator 31 as required by using the brake ECU 30 to controlthe braking force of the vehicle such that the acceleration of thevehicle matches the target acceleration Gtgt.

(Method of Operating Operation Device)

Next, a detailed method of operating the switches 61 to 66 of theoperation device 60 is described.

The main switch 61 is a switch to be operated by the driver when the ACCis started or finished. Each time the main switch 61 is pressed, thestate of the main switch 61 alternates between an ON state and an OFFstate. When the main switch 61 is switched from the OFF state to the ONstate, the driving support ECU 10 starts the ACC. Meanwhile, when themain switch 61 is switched from the ON state to the OFF state, thedriving support ECU 10 finishes the ACC.

The cancel switch 62 is a switch to be operated by the driver when theACC is temporarily stopped (temporarily canceled). Each time the cancelswitch 62 is pressed, the state of the cancel switch 62 alternatesbetween an ON state and an OFF state. When the cancel switch 62 isswitched to the ON state in a situation in which the main switch 61 isin the ON state (during execution of the ACC), the driving support ECU10 temporarily stops the ACC.

The inter-vehicle time setting switch 63 is a switch to be operated bythe driver when the target inter-vehicle time Ttgt in thefollowing-travel-mode control is set. The driver can select one of thethree levels of time (long, medium, and short) as the targetinter-vehicle time Ttgt.

The resume/acceleration switch 64 is a switch to be operated by thedriver when the ACC is resumed after the ACC is temporarily stopped. Theresume/acceleration switch 64 is hereinafter simply referred to as“resume switch 64”. The resume switch 64 is in an ON state when theresume switch 64 has been pressed by the driver, and is in an OFF statewhen the resume switch 64 has not been pressed by the driver. When theresume switch 64 is changed from the OFF state to the ON state in asituation in which the main switch 61 is in the ON state and the cancelswitch 62 is in the ON state (that is, a situation in which the ACC istemporarily stopped), the driving support ECU 10 resumes the ACC. Whenthe ACC is resumed, the driving support ECU 10 changes the state of thecancel switch 62 to the OFF state.

In a case in which there is a following target vehicle when the ACC isresumed, the driving support ECU 10 resumes following-travel-modecontrol. In contrast, in a case in which there is no following targetvehicle when the ACC is resumed, the driving support ECU 10 resumes theconstant-speed-travel-mode control by using the set speed Vset at thetime when the ACC was temporarily stopped.

As described above, the resume switch 64 is also operated when thevehicle is started in a case in which the own vehicle has stoppedimmediately behind the following target vehicle (a) duringfollowing-travel-mode control.

Further, the resume switch 64 is also a switch to be operated by thedriver when the set speed Vset is increased. Therefore, in a case inwhich the constant-speed-travel-mode control is being executed, when theresume switch 64 is switched to the ON state, the driving support ECU 10increases the set speed Vset by a predetermined speed change amount.

The set/deceleration switch 65 is a switch to be operated by the driverwhen the set speed Vset is set. The set/deceleration switch 65 ishereinafter simply referred to as “set switch 65”. The set switch 65 isin an ON state when the set switch 65 has been pressed by the driver,and is in an OFF state when the set switch 65 has not been pressed bythe driver. When the set switch 65 is changed from the OFF state to theON state after the ACC is started, the driving support ECU 10 sets theset speed Vset to “the vehicle speed SPD at the time when the set switch65 was switched to the ON state (that is, at the time when the driverpressed the set switch 65)”.

Further, the set switch 65 is also a switch to be operated by the driverwhen the set speed Vset is decreased. In a case in which theconstant-speed-travel-mode control is being executed, when the setswitch 65 is switched to the ON state, the driving support ECU 10decreases the set speed Vset by a predetermined speed change amount.

As described later, the automatic start switch 66 is a switch to beoperated by the driver when a response operation (approval operation) isperformed in response to an inquiry as to whether or not to execute theautomatic start control. The automatic start switch 66 is in an ON statewhen the automatic start switch 66 has been pressed by the driver, andis in an OFF state when the automatic start switch 66 has not beenpressed by the driver. In the case in which the inquiry has beenperformed, when the automatic start switch 66 is in the ON state, thedriving support ECU 10 determines that the driver has performed theresponse operation in response to the inquiry (that is, determines thatthe driver desires the automatic start control to be executed).

In a case in which the driver performs a specific cancel operation(e.g., two consecutive pressing operations within a predetermined time)on the automatic start switch 66 when the operation mode of theautomatic start control is in the ON mode, the operation mode of theautomatic start control can be changed to the OFF mode.

(Overview of Operation)

As described above, depending on the travel state of the own vehicle,the driver may or may not desire the automatic start control to beexecuted. Therefore, when the own vehicle has stopped in response to thestopping of the following target vehicle during execution of the ACC andthe operation mode of the automatic start control is set to the OFFmode, the control apparatus according to the present embodimentdetermines whether or not the current travel state of the own vehicle isa state in which there is a high probability that the driver desires theautomatic start control to be executed (hereinafter referred to as“specific state”).

For example, when the own vehicle is traveling on a limited-access road,the control apparatus determines that the current travel state of theown vehicle is the specific state. As another example, when the ownvehicle is traveling on a general road and there are no moving objects(pedestrians or two-wheeled vehicles) around the own vehicle, thecontrol apparatus determines that the current travel state of the ownvehicle is the specific state. When it is determined that the currenttravel state of the own vehicle is the specific state, the controlapparatus causes the notification device (the display 51 and the speaker52) to issue a notification for inquiring whether or not the driverdesires the automatic start control to be executed.

Even when the above-mentioned inquiry is performed, some drivers desireto start the own vehicle by performing a driving operation themselves.Therefore, the control apparatus determines whether or not the driverhas performed the response operation by operating the automatic startswitch 66 in response to the inquiry.

When the driver has performed the response operation, the controlapparatus sets the operation mode of the automatic start control to theON mode. In contrast, when the driver has not performed the responseoperation, the control apparatus sets the operation mode of theautomatic start control to the OFF mode. Thus, the control apparatus candetermine whether to execute the automatic start control in accordancewith the desire of the driver.

(Operation)

The CPU 101 of the driving support ECU 10 (hereinafter simply referredto as “CPU”) is configured to execute the routine illustrated in FIG. 2each time a predetermined time elapses.

The CPU acquires the object information from the ambient sensor 14 andstores the acquired object information in the RAM 103 by executing aroutine (not shown) each time a predetermined time elapses. The CPU alsoacquires the road information (including the road type) from the map DB42 via the navigation ECU 40 and stores the acquired road information inthe RAM 103 by executing a routine (not shown) each time a predeterminedtime elapses. Information on the periphery of the vehicle including “theobject information and the road information” may be referred to as“vehicle peripheral information”.

In addition, when starting following-travel-mode control, the CPUexecutes an initialization routine (not shown), and sets the values ofvarious flags described later to “0” (clears the flags).

When a predetermined timing is reached, the CPU starts the processingfrom Step 200 of FIG. 2, and proceeds to Step 201 to determine whetheror not following-travel-mode control is being executed. When thefollowing-travel-mode control is not being executed, the CPU makes adetermination of “No” in Step 201, and directly proceeds to Step 295 totemporarily finish this routine.

In contrast, when the following-travel-mode control is being executed,the CPU makes a determination of “Yes” in Step 201, and proceeds to Step202 to determine whether or not a first automatic start flag XA1 is “0”.When the value of the first automatic start flag XA1 is “0”, thisindicates that the operation mode of the automatic start control is inthe OFF mode in a situation in which the vehicle is traveling on alimited-access road, and when the value is “1”, this indicates that theoperation mode of the automatic start control is in the ON mode in asituation in which the vehicle is traveling on a limited-access road.

In this case, when it is assumed that the value of the first automaticstart flag XA1 is “0”, the CPU makes a determination of “Yes” in Step202, and proceeds to Step 203 to determine whether or not the value of afirst inquiry flag XB1 is “0”. The value of the first inquiry flag XB1is set to “1” when the processing of Step 207, which is described later,is executed (that is, when the processing of issuing an inquiry to thedriver about whether or not to execute the automatic start control isperformed). The value of the first inquiry flag XB1 is set to “0” whenany one of “first finish condition and first reset condition” describedlater is satisfied after the processing of Step 207 is executed.

When the value of the first inquiry flag XB1 is “0”, the CPU makes adetermination of “Yes” in Step 203, and proceeds to Step 204 todetermine whether or not the own vehicle is stopped (that is, whether ornot the vehicle speed SPD is zero). When the own vehicle is not stopped,the CPU makes a determination of “No” in Step 204, and directly proceedsto Step 295 to temporarily finish this routine.

When the own vehicle is stopped, the CPU makes a determination of “Yes”in Step 204, and proceeds to Step 205 to determine, based on the vehicleperipheral information, whether or not a predetermined first specificstate condition is satisfied. This condition is a condition fordetermining whether or not the current travel state of the own vehicleis the specific state, in which there is a high probability that thedriver desires the automatic start control to be executed. The firstspecific state condition is satisfied when the following condition A1 issatisfied. The CPU determines whether or not the condition A1 issatisfied based on the road information (including the road type).

(Condition A1): The own vehicle is traveling on a limited-access road(the own vehicle is located on a limited-access road).

When the first specific state condition is not satisfied, the CPU makesa determination of “No” in Step 205, and directly proceeds to Step 295to temporarily finish this routine.

In contrast, when the first specific state condition is satisfied, theCPU makes a determination of “Yes” in Step 205, and proceeds to Step 206to determine whether or not a predetermined start-ready condition issatisfied. The start-ready condition is satisfied when the driver is notoperating the brake pedal 12 a.

When the start-ready condition is not satisfied, this means that thedriver is intentionally operating the brake pedal 12 a to stop the ownvehicle. Therefore, it is considered that the driver desires to drivethe vehicle under his or her own operation. Therefore, the CPU makes adetermination of “No” in Step 206, and proceeds directly to Step 295 totemporarily finish this routine. In this case, the processing of issuingan inquiry to the driver about whether or not the driver desires theautomatic start control to be executed (the processing of Step 207) isnot performed.

In contrast, when the start-ready condition is satisfied, the CPU makesa determination of “Yes” in Step 206, and sequentially executes theprocessing of Step 207 and Step 208 described later. Then, the CPUproceeds to Step 209.

Step 207: The CPU causes the notification device (the display 51 and thespeaker 52) to execute processing of issuing an inquiry to the driverabout whether or not the driver desires the automatic start control tobe executed (hereinafter simply referred to as “inquiry processing”).Specifically, the CPU causes the display 51 to display a message forinquiring whether or not to execute the automatic start control, andcauses the speaker 52 to utter the message. Further, the CPU may causethe display 51 to display a message to the effect that the operationmode of the automatic start control can be turned to the ON mode bypressing the automatic start switch 66, and cause the speaker 52 toutter the message. Thus, the CPU can issue an inquiry (propose) to thedriver about execution of the automatic start control in accordance withthe travel state of the vehicle.

Step 208: The CPU Sets the Value of the First Inquiry Flag XB1 to “1”.

When the CPU proceeds to Step 209, the CPU determines whether or not thedriver has performed the response operation in response to the inquiryprocessing (whether or not the state of the automatic start switch 66has been turned on). When the driver has performed the responseoperation (approval operation) in response to the proposal to executethe automatic start control, this means that the driver desires theautomatic start control to be executed. Therefore, the CPU makes adetermination of “Yes” in Step 209, and proceeds to Step 210 to set thevalue of the first automatic start flag XA1 to “1”. Specifically, theoperation mode of the automatic start control is set to the ON mode.Then, the CPU proceeds to Step 295 to temporarily finish this routine.As a result, the CPU makes a determination of “Yes” in Step 405 of theroutine of FIG. 4 described later, and hence the automatic start controlis executed.

In contrast, when the response operation has not been performed by thedriver (when the state of the automatic start switch 66 remains in theOFF state), the CPU makes a determination of “No” in Step 209, andproceeds to Step 211 to determine whether or not “an elapsed time Em1from when the inquiry processing is performed in Step 207” is equal toor longer than a predetermined first time threshold value Tm1. When theelapsed time Em1 is less than the first time threshold value Tm1, theCPU makes a determination of “No” in Step 211, and returns to Step 209.

When the elapsed time Em1 is equal to or longer than the first timethreshold value Tm1, the CPU considers that the driver has not approvedexecution of the automatic start control (that is, the driver has turneddown execution of the automatic start control). Therefore, the CPU makesa determination of “Yes” in Step 211, and proceeds to Step 212 to setthe value of the first automatic start flag XA1 to “O”. That is, theoperation mode of the automatic start control is set to the OFF mode.Then, the CPU proceeds to Step 295 to temporarily finish this routine.Thus, in a situation in which the own vehicle is traveling on alimited-access road, the CPU makes a determination of “No” in Step 405of the routine of FIG. 4 described later, and hence the automatic startcontrol is not executed.

Thus, when the CPU restarts the routine of FIG. 2 from Step 200 afterthe value of the first automatic start flag XA1 has been set to “1” andproceeds to Step 202, the CPU makes a determination of “No” and proceedsto Step 213.

In Step 213, the CPU determines whether or not a predetermined firstfinish condition is satisfied. The first finish condition is satisfiedwhen any one of the following conditions B1 to B4 is satisfied.

(Condition B1): The vehicle speed SPD of the own vehicle is equal to orhigher than a predetermined speed threshold value Vth (e.g., 60 km/h).Specifically, there is a high probability that the traffic congestion ofthe limited-access road has been eliminated.

(Condition B2): The own vehicle has moved from a limited-access road toa general road.

(Condition B3): The driver has performed the specific cancel operation(e.g., two consecutive pressing operations within a predetermined time)on the automatic start switch 66.

(Condition B4): The driver has changed the state of the main switch 61to the OFF state by pressing the main switch 61. That is, the driver hasfinished the ACC.

When the first finish condition is not satisfied, the CPU makes adetermination of “No” in Step 213, and directly proceeds to Step 295 totemporarily finish this routine. As a result, the value of the firstautomatic start flag XA1 is maintained at “1”. That is, in a situationin which the own vehicle is traveling on a limited-access road, theoperation mode of the automatic start control is maintained in the ONmode. Therefore, the automatic start control is executed each time theown vehicle stops in response to the stopping of the following targetvehicle (a) on a limited-access road (see a determination of “Yes” inStep 405 of the routine of FIG. 4).

In contrast, when the first finish condition is satisfied, the CPU makesa determination of “Yes” in Step 213, and proceeds to Step 214 to setthe value of the first automatic start flag XA1 to “0”. That is, theoperation mode of the automatic start control is changed from the ONmode to the OFF mode. Further, the CPU sets the value of the firstinquiry flag XB1 to “0”. Then, the CPU proceeds to Step 295 totemporarily finish this routine. As a result, in a situation in whichthe own vehicle is traveling on a limited-access road, the CPU makes adetermination of “No” in Step 405 of the routine of FIG. 4 describedlater, and hence the automatic start control is not executed.

It is assumed that the CPU restarts the routine of FIG. 2 from Step 200after the value of the first inquiry flag XB1 has been set to “1” andthe value of the first automatic start flag XA1 has been set to “0” asdescribed above (Step 208, Step 209: No, Step 211: Yes, and Step 212).When the CPU proceeds to Step 203, the CPU makes a determination of“No”, and proceeds to Step 215.

In Step 215, the CPU determines whether or not a predetermined firstreset condition is satisfied. The first reset condition is satisfiedwhen any one of the following conditions C1 to C4 is satisfied.

(Condition C1): The vehicle speed SPD of the own vehicle is equal to orhigher than a predetermined speed threshold value Vth (e.g., 60 km/h).Specifically, there is a high probability that the traffic congestion ofthe limited-access road has been eliminated.

(Condition C2): The own vehicle has moved from a limited-access road toa general road.

(Condition C3): An elapsed time Et1 from when the value of the firstinquiry flag XB1 became “1” (that is, the time at which the processingof Step 208 was executed) has become equal to or longer than apredetermined second time threshold value Tm2.

(Condition C4): The driver has changed the state of the main switch 61to the OFF state by pressing the main switch 61. That is, the driver hasfinished the ACC.

When the first reset condition is not satisfied, the CPU makes adetermination of “No” in Step 215, and directly proceeds to Step 295 totemporarily finish this routine. Therefore, the value of the firstinquiry flag XB1 is maintained at “1”, and hence the CPU makes adetermination of “No” in Step 203. Therefore, on a limited-access road,the inquiry processing (processing of Step 207) is not performed atleast until the first reset condition is satisfied. For example, in acase in which the own vehicle is traveling in a traffic-congestionsection, when the driver has not performed the response operation inresponse to the inquiry processing (the driver has once turned downexecution of the automatic start control), the inquiry processing is notperformed until the above-mentioned condition C3 is satisfied.Therefore, the likelihood that the driver is bothered by the inquiryprocessing can be reduced.

In contrast, when the first reset condition is satisfied, the CPU makesa determination of “Yes” in Step 215, and proceeds to Step 216 to setthe value of the first inquiry flag XB1 to “0”. Then, the CPU proceedsto Step 295 to temporarily finish this routine.

The CPU s also configured to execute the routine illustrated in FIG. 3each time a predetermined time elapses.

When a predetermined timing is reached, the CPU starts the processingfrom Step 300 of FIG. 3, and proceeds to Step 301 to determine whetheror not following-travel-mode control is being executed. When thefollowing-travel-mode control is not being executed, the CPU makes adetermination of “No” in Step 301, and directly proceeds to Step 395 totemporarily finish this routine.

In contrast, when the following-travel-mode control is being executed,the CPU makes a determination of “Yes” in Step 301, and proceeds to Step302 to determine whether or not a second automatic start flag XA2 is“O”. When the value of the second automatic start flag XA2 is “0”, thisindicates that the operation mode of the automatic start control is inthe OFF mode in a situation in which the vehicle is traveling on ageneral road, and when the value is “1”, this indicates that theoperation mode of the automatic start control is in the ON mode in asituation in which the vehicle is traveling on a general road.

In this case, when it is assumed that the value of the second automaticstart flag XA2 is “0”, the CPU makes a determination of “Yes” in Step302, and proceeds to Step 303 to determine whether or not the value of asecond inquiry flag XB2 is “0”. The value of the second inquiry flag XB2is set to “1” when the processing of Step 307, which is described later,is executed (that is, when the processing of issuing an inquiry to thedriver about whether or not to execute the automatic start control isperformed). The value of the second inquiry flag XB2 is set to “0” whenany one of “second finish condition and second reset condition”described later is satisfied after the processing of Step 307 isexecuted.

When the value of the second inquiry flag XB2 is “0”, the CPU makes adetermination of “Yes” in Step 303, and proceeds to Step 304 todetermine whether or not the own vehicle is stopped (that is, whether ornot the vehicle speed SPD is zero). When the own vehicle is not stopped,the CPU makes a determination of “No” in Step 304, and directly proceedsto Step 395 to temporarily finish this routine.

When the own vehicle is stopped, the CPU makes a determination of “Yes”in Step 304, and proceeds to Step 305 to determine, based on the vehicleperipheral information, whether or not a predetermined second specificstate condition is satisfied. This condition is a condition fordetermining whether or not the current travel state of the own vehicleis the specific state in which there is a high probability that thedriver desires the automatic start control to be executed. The secondspecific state condition is satisfied when the following conditions D1and D2 are both satisfied. The CPU determines whether or not thecondition D1 is satisfied based on the road information (including theroad type). Further, the CPU determines whether or not the condition D2is satisfied based on the object information (including the type of theobject).

(Condition D1): The own vehicle is traveling on a general road (the ownvehicle is positioned on a general road).

(Condition D2): A predetermined moving object (pedestrian and/ortwo-wheeled vehicle) is not detected within a predetermined distancerange from the own vehicle.

When the second specific state condition is not satisfied, the CPU makesa determination of “No” in Step 305, and directly proceeds to Step 395to temporarily finish this routine.

In contrast, when the second specific state condition is satisfied, theCPU makes a determination of “Yes” in Step 305, and proceeds to Step 306to determine whether or not the above-mentioned start-ready condition issatisfied.

When the start-ready condition is not satisfied, the CPU makes adetermination of “No” in Step 306, and directly proceeds to Step 395 totemporarily finish this routine.

In contrast, when the start-ready condition is satisfied, the CPU makesa determination of “Yes” in Step 306, and executes the processing ofStep 307 and Step 308 described later in order. Then, the CPU proceedsto Step 309.

Step 307: The CPU causes the notification device (the display 51 and thespeaker 52) to execute the inquiry processing as described above.

Step 308: The CPU sets the value of the second inquiry flag XB2 to “1”.

When the CPU proceeds to Step 309, the CPU determines whether or not thedriver has performed the response operation in response to the inquiryprocessing (determines whether or not the automatic start switch 66 hasbecome the ON state). When the response operation has been performed bythe driver, the CPU makes a determination of “Yes” in Step 309, andproceeds to Step 310 to set the value of the second automatic start flagXA2 to “1”. Specifically, the operation mode of the automatic startcontrol is set to the ON mode. Then, the CPU proceeds to Step 395 totemporarily finish this routine. As a result, the CPU makes adetermination of “Yes” in Step 405 of the routine of FIG. 4 describedlater, and hence the automatic start control is executed.

In contrast, when the response operation has not been performed by thedriver (the automatic start switch 66 remains in the OFF state), the CPUmakes a determination of “No” in Step 309, and proceeds to Step 311 todetermine whether or not “an elapsed time Em2 from when the inquiryprocessing is performed in Step 307” is equal to or longer than thefirst time threshold value Tm1. When the elapsed time Em2 is less thanthe first time threshold value Tm1, the CPU makes a determination of“No” in Step 311, and returns to Step 309.

When the elapsed time Em2 is equal to or longer than the first timethreshold value Tm1, the CPU makes a determination of “Yes” in Step 311,and proceeds to Step 312 to set the value of the second automatic startflag XA2 to “0”. That is, the operation mode of the automatic startcontrol is set to the OFF mode. Then, the CPU proceeds to Step 395 totemporarily finish this routine. Thus, in a situation in which the ownvehicle is traveling on a general road, the CPU makes a determination of“No” in Step 405 of the routine of FIG. 4 described later, and hence theautomatic start control is not executed.

Thus, when the CPU restarts the routine of FIG. 3 from Step 300 afterthe value of the second automatic start flag XA2 has been set to “1” andproceeds to Step 302, the CPU makes a determination of “No” and proceedsto Step 313.

In Step 313, the CPU determines whether or not a predetermined secondfinish condition is satisfied. The second finish condition is satisfiedwhen any one of the following conditions E1 to E4 is satisfied.

(Condition E1): In a situation in which the own vehicle is stopped, apredetermined moving object (pedestrian and/or two-wheeled vehicle) isdetected within a predetermined distance range from the own vehicle.

(Condition E2): The own vehicle has moved from a general road to alimited-access road.

(Condition E3): The driver has performed the specific cancel operation(e.g., two consecutive pressing operations within a predetermined time)on the automatic start switch 66.

(Condition E4): The driver has changed the state of the main switch 61to the OFF state by pressing the main switch 61. That is, the driver hasfinished the ACC.

When the second finish condition is not satisfied, the CPU makes adetermination of “No” in Step 313, and directly proceeds to Step 395 totemporarily finish this routine. As a result, the value of the secondautomatic start flag XA2 is maintained at “1”. That is, in a situationin which the own vehicle is traveling on a general road, the operationmode of the automatic start control is maintained in the ON mode.Therefore, the automatic start control is executed each time the ownvehicle stops in response to the stopping of the following targetvehicle (a) on a general road (see a determination of “Yes” in Step 405of the routine of FIG. 4).

In contrast, when the second finish condition is satisfied, the CPUmakes a determination of “Yes” in Step 313, and proceeds to Step 314 toset the value of the second automatic start flag XA2 to “0”. That is,the operation mode of the automatic start control is changed from the ONmode to the OFF mode. Further, the CPU sets the value of the secondinquiry flag XB2 to “0”. Then, the CPU proceeds to Step 395 totemporarily finish this routine. As a result, in a situation in whichthe own vehicle is traveling on a general road, the CPU makes adetermination of “No” in Step 405 of the routine of FIG. 4 describedlater, and hence the automatic start control is not executed.

It is assumed that the CPU restarts the routine of FIG. 3 from Step 300after the value of the second inquiry flag XB2 has been set to “1” andthe value of the second automatic start flag XA2 has been set to “0” asdescribed above (Step 308, Step 309: No, Step 311: Yes, and Step 312).When the CPU proceeds to Step 303, the CPU makes a determination of“No”, and proceeds to Step 315.

In Step 315, the CPU determines whether or not a predetermined secondreset condition is satisfied. The second reset condition is satisfiedwhen any one of the following conditions F1 to F3 is satisfied.

(Condition F1): The own vehicle has moved from a general road to alimited-access road.

(Condition F2): An elapsed time Et2 from when the value of the secondinquiry flag XB2 became “1” (that is, the time at which the processingof Step 308 was executed) has become equal to or longer than thepredetermined second time threshold value Tm2.

(Condition F3): The driver has changed the state of the main switch 61to the OFF state by pressing the main switch 61. That is, the driver hasfinished the ACC.

When the second reset condition is not satisfied, the CPU makes adetermination of “No” in Step 315, and directly proceeds to Step 395 totemporarily finish this routine. Accordingly, the value of the secondinquiry flag XB2 is maintained at “1”, and hence the CPU makes adetermination of “No” in Step 303. Therefore, on a general road, theinquiry processing (processing of Step 307) is not performed at leastuntil the second reset condition is satisfied.

In contrast, when the second reset condition is satisfied, the CPU makesa determination of “Yes” in Step 315, and proceeds to Step 316 to setthe value of the second inquiry flag XB2 to “0”. Then, the CPU proceedsto Step 395 to temporarily finish this routine.

The CPU is also configured to execute the routine illustrated in FIG. 4each time a predetermined time elapses.

When a predetermined timing is reached, the CPU starts the processingfrom Step 400 of FIG. 4, and proceeds to Step 401 to determine whetheror not following-travel-mode control is being executed. When thefollowing-travel-mode control is not being executed, the CPU makes adetermination of “No” in Step 401, and directly proceeds to Step 495 totemporarily finish this routine.

In contrast, when the following-travel-mode control is being executed,the CPU makes a determination of “Yes” in Step 401, and proceeds to Step402 to determine whether or not the own vehicle is stopped (that is, thevehicle speed SPD is zero). When the own vehicle is not stopped, the CPUmakes a determination of “No” in Step 402, and proceeds directly to Step495 to temporarily finish this routine.

When the own vehicle is stopped, the CPU makes a determination of “Yes”in Step 402, and proceeds to Step 403 to determine whether or not thefollowing target vehicle (a) has started. Specifically, the CPUdetermines that the following target vehicle (a) has started when therelative speed Vfx (a) of the following target vehicle (a) has becomeequal to or higher than a predetermined start threshold value.

When the following target vehicle (a) has not started (that is, thefollowing target vehicle (a) is stopped), the CPU makes a determinationof “No” in Step 403, and proceeds directly to Step 495 to temporarilyfinish this routine.

In contrast, when the following target vehicle (a) has started, the CPUmakes a determination of “Yes” in Step 403, and proceeds to Step 404 todetermine whether the above-mentioned start-ready condition issatisfied.

When the start-ready condition is not satisfied, the CPU makes adetermination of “No” in Step 404, and proceeds directly to Step 495 totemporarily finish this routine.

In contrast, when the start-ready condition is satisfied, the CPU makesa determination of “Yes” in Step 404, and proceeds to Step 405 todetermine whether any one of the following conditions G1 and G2 issatisfied.

(Condition G1): The value of the first automatic start flag XA1 is “1”.

(Condition G2): The value of the second automatic start flag XA2 is “1”.

When any one of the condition G1 and the condition G2 is satisfied, theCPU makes a determination of “Yes” in Step 405, and proceeds to Step 406to execute the automatic start control. Specifically, the CPU controlsthe brake actuator 31 by using the brake ECU 30 to release the brakingforce, and controls the engine actuator 21 by using the engine ECU 20 tostart the own vehicle. Then, the CPU proceeds to Step 495 to temporarilyfinish this routine. Then, the CPU continues the following-travel-modecontrol with respect to the following target vehicle (a).

In contrast, when none of the condition G1 and the condition G2 issatisfied, the CPU makes a determination of “No” in Step 405, andproceeds to Step 407 to determine whether or not a predeterminedoperation has been performed. The predetermined operation is any one ofthe above-mentioned operation 1 (operation of pressing the resume switch64) and operation 2 (operation of stepping on the accelerator pedal 11a). When the predetermined operation has been performed by the driver,the CPU makes a determination of “Yes” in Step 407, and proceeds to Step408 to start the own vehicle. Specifically, the CPU controls the brakeactuator 31 by using the brake ECU 30 to release the braking force, andcontrols the engine actuator 21 by using the engine ECU 20 to start theown vehicle. Then, the CPU proceeds to Step 495 to temporarily finishthis routine. Then, the CPU continues the following-travel-mode controlwith respect to the following target vehicle (a).

In contrast, when the predetermined operation has not been performed bythe driver, the CPU makes a determination of “No” in Step 407, andproceeds to Step 409. In Step 409, the CPU issues an operation requestto the driver. Specifically, the CPU causes the display 51 to display amessage for requesting the predetermined operation (any one of theabove-mentioned operation 1 and operation 2), and causes the speaker 52to utter the message. Then, the CPU returns to Step 407.

As described above, when the own vehicle has stopped in response to thestopping of the following target vehicle (a) during execution of the ACCand the operation mode of the automatic start control is set to the OFFmode, the control apparatus determines whether or not the current travelstate of the own vehicle is the specific state in which there is a highprobability that the driver desires the automatic start control to beexecuted.

When the own vehicle is stopped on a limited-access road, there is ahigh probability that the limited-access road is congested. Therefore,it is considered that the driver desires the automatic start control tobe executed. In this case, the control apparatus determines that thecurrent travel state of the own vehicle is the specific state.

In contrast, in a case in which the own vehicle is stopped on a generalroad, when a predetermined moving object (pedestrian and/or two-wheeledvehicle) exists around the vehicle, the driver may not desire theautomatic start control to be executed. However, when there is nopredetermined moving object around the vehicle, there is a highlikelihood that the driver desires the automatic start control to beexecuted. Therefore, the control apparatus determines that the currenttravel state of the own vehicle is the specific state when the ownvehicle is traveling on a general road and there is no predeterminedmoving object around the own vehicle.

When it is determined that the current travel state of the own vehicleis the specific state, the control apparatus causes the notificationdevice (the display 51 and the speaker 52) to issue a notification forinquiring whether or not the driver desires the automatic start controlto be executed. Thus, the control apparatus can issue an inquiry(propose) to the driver about execution of the automatic start controlin accordance with the current travel state of the vehicle.

The control apparatus sets the operation mode of the automatic startcontrol to the ON mode when the driver has performed the responseoperation (operation of pressing the automatic start switch 66) inresponse to the inquiry. Therefore, when the preceding vehicle starts,the automatic start control is executed in response to the starting ofthe preceding vehicle. In contrast, when the driver has not performedthe response operation in response to the inquiry, the control apparatussets the operation mode of the automatic start control to the OFF mode.In this case, the driver can start the own vehicle by performing thepredetermined operation (any one of the operation 1 and the operation2). Therefore, the driver can start the own vehicle at a timing at whichthe predetermined operation is performed. Thus, the control apparatuscan determine whether or not to execute the automatic start control inaccordance with the desire of the driver by inquiring whether or not theautomatic start control is to be executed.

Further, when the driver has performed the response operation (when theoperation mode of the automatic start control has been set to the ONmode), the control apparatus maintains the operation mode of theautomatic start control in the ON mode until the predetermined finishcondition (i.e., the first finish condition or the second finishcondition) is satisfied. The control apparatus changes the operationmode of the automatic start control from the ON mode to the OFF modewhen the predetermined finish condition is satisfied.

For example, it is assumed that the own vehicle is traveling in atraffic-congestion section on a limited-access road. In this case, theown vehicle travels at a low speed and stops repeatedly. Therefore, thecondition B1 of the first finish condition is not satisfied. In such asituation, when the driver once performs the response operation, theoperation mode of the automatic start control is maintained in the ONmode until the own vehicle passes through the traffic-congestionsection. Therefore, on a limited-access road, the automatic startcontrol is automatically executed each time the own vehicle stops inresponse to the stopping of the following target vehicle (a). In otherwords, the driver is not required to perform the response operation(operation of pressing the automatic start switch 66) each time the ownvehicle stops. Therefore, the convenience of the driver is improved.

For example, it is assumed that the own vehicle is traveling in atraffic-congestion section on a general road. In such a situation, whenthe driver once performs the response operation, the operation mode ofthe automatic start control is maintained in the ON mode until thesecond finish condition is satisfied. When a pedestrian is detectedaround the own vehicle in a situation in which the own vehicle hasstopped on a general road, the condition E1 of the second finishcondition is satisfied. In this case, the operation mode of theautomatic start control is changed to the OFF mode, and hence theautomatic start control is not executed on the general road. Therefore,the likelihood of the own vehicle approaching the pedestrian around theown vehicle can be reduced.

The present disclosure is not limited to at least one embodimentdescribed above, and various modification examples can be adopted withinthe scope of the present disclosure.

Modification Example 1

The first specific state condition is not limited to the exampledescribed above. The first specific state condition may include thefollowing condition A2. (Condition A2): The own vehicle is traveling ina traffic-congestion section.

The driving support ECU 10 may determine whether or not the own vehicleis traveling in a traffic-congestion section based on the road trafficinformation (including the traffic-congestion section information)received via the communication device 44.

The driving support ECU 10 may also be configured to store informationon the “vehicle speed SPD for the latest predetermined period (e.g., 5minutes)” of the own vehicle in the RAM 103. Further, the drivingsupport ECU 10 may determine that the own vehicle is traveling in atraffic-congestion section when both the following conditions H1 and H2are satisfied. The conditions H1 and H2 are conditions for determiningwhether or not the own vehicle travels at a low speed and stopsrepeatedly.

(Condition H1): The minimum value of the vehicle speed SPD in thepredetermined period is “zero”.

(Condition H2): The maximum value of the vehicle speed SPD in thepredetermined period is equal to or less than a predetermined low speedthreshold value.

As another example, the driving support ECU 10 may determine that theown vehicle is traveling in a traffic-congestion section based on theobject information (information on the following target vehicle (a)).The driving support ECU 10 may determine that the own vehicle istraveling in a traffic-congestion section when both of the followingconditions I1 and I2 are satisfied.

(Condition I1): The minimum value of the vehicle speed (Vs) of thefollowing target vehicle (a) in the latest predetermined period (e.g., 5minutes) is “zero”.

(Condition I2): The maximum value of the vehicle speed (Vs) of thefollowing target vehicle (a) in a predetermined period is equal to orless than the predetermined low speed threshold value.

With this configuration, the inquiry processing is executed when it isconsidered that there is a high probability that the driver desires theautomatic start control to be executed on a limited-access road (whenthe own vehicle is traveling in a traffic-congestion section). Further,when the driver performs the response operation in response to theinquiry processing, the operation mode of the automatic start control isset to the ON mode.

Modification Example 2

In addition, the first specific state condition may include thefollowing condition A3.

(Condition A3): When it is assumed that the automatic start control isto be executed, a predetermined moving object that may approach the ownvehicle is not detected. The predetermined moving object is, forexample, another vehicle (b) attempting to enter between the own vehicleand the following target vehicle (a) by changing lanes.

The camera sensor 14 b recognizes a partition line of the road (thetravel lane along which the vehicle is traveling and the adjacent laneadjacent to the travel lane) based on the image data, and identifies apositional relationship between the object and the road (the travel laneand the adjacent lane). Further, the CPU of the driving support ECU 10determines whether or not another vehicle (b) exists in the adjacentlane based on the object information. When the direction of the relativelateral speed Vfy(b) of the another vehicle (b) is toward the travellane and the magnitude of the relative lateral speed Vfy(b) is equal toor more than a predetermined lateral speed threshold value, the CPUdetermines that the another vehicle (b) is attempting to enter betweenthe own vehicle and the following target vehicle (a) by changing lanes.In this case, the above-mentioned condition A3 is not satisfied.

With this configuration, the inquiry processing is not executed whenanother vehicle (b) is attempting to enter between the own vehicle andthe following target vehicle (a) in a situation in which the own vehicleis stopped. As a result, the operation mode of the automatic startcontrol is not changed to the ON mode. Therefore, it is possible toprevent the own vehicle from approaching the another vehicle (b).

Modification Example 3

The second specific state condition is not limited to the exampledescribed above. The second specific state condition may include thefollowing condition D3.

(Condition D3): The own vehicle is traveling in a traffic-congestionsection.

As described above, the CPU may determine whether or not the own vehicleis traveling in a traffic-congestion section based on any one of theroad traffic information (including information on a traffic-congestionsection), the information on the vehicle speed SPD, and the objectinformation (information on the following target vehicle (a)).

Modification Example 4

The second specific state condition may include the following conditionD4.

(Condition D4): There is no predetermined stop point within apredetermined distance range ahead of the own vehicle. Thispredetermined stop point is a point at which the own vehicle is to stop,and includes, for example, an intersection and a railroad crossing.

With this configuration, the inquiry processing is not executed whenthere is a predetermined stop point ahead of the own vehicle on ageneral road. Therefore, when there is the predetermined stop pointahead of the own vehicle, the operation mode of automatic start controlis not changed to the ON mode. As a result, it is possible to inhibitthe own vehicle from advancing past the stop point.

Modification Example 5

The driving support ECU 10 may be configured to execute the automaticstart control only on limited-access roads. That is, the routine of FIG.3 may be omitted.

Modification Example 6

The driving support ECU 10 may be configured to execute the automaticstart control only on general roads. That is, the routine of FIG. 2 maybe omitted.

Modification Example 7

The first specific state condition and the second specific statecondition may each be a condition including only the following conditionJ1.

(Condition J1): A predetermined moving object (pedestrian and/ortwo-wheeled vehicle) is not detected within a predetermined distancerange from the own vehicle.

Modification Example 8

The driving support ECU 10 may be configured to execute the automaticstart control without distinguishing whether the road on which the ownvehicle is traveling is a limited-access road or a general road. Forexample, when the own vehicle is traveling in a traffic-congestionsection, the driving support ECU 10 may determine that the currenttravel state of the own vehicle is the specific state, and cause thenotification device to execute the inquiry processing.

Modification Example 9

The inquiry processing may be performed by using any one of the display51 and the speaker 52. Further, a message for inquiring whether or notto execute the automatic start control may be displayed on a displayother than the display 51. For example, the driving support ECU 10 maydisplay the above-mentioned message on the touch panel 43.

Modification Example 10

The switch for performing the response operation (approval operation) inStep 209 and Step 309 is not limited to the above-mentioned example, andmay be any switch/button that can be operated when the driver respondsto the inquiry processing. Specifically, in place of the automatic startswitch 66, a switch/button described below may be employed in order toperform the response operation.

For example, the driving support ECU 10 may cause the touch panel 43 todisplay a message for inquiring whether or not to execute the automaticstart control and a response button. In this case, when the driverperforms a touch operation on the response button, the CPU sets theoperation mode of the automatic start control to the ON mode. As anotherexample, any of the switches 61 to 65 may further have a function ofresponding to the inquiry processing. Further, a switch/button forapproving or instructing execution of control other than ACC (e.g., lanekeeping assist (LKA) and parking assist control) may further have afunction of performing the response operation of Step 209 and Step 309.

What is claimed is:
 1. A vehicle travel control apparatus, comprising:an information acquisition device configured to acquire vehicleperipheral information including object information on an objectexisting around an own vehicle; a vehicle controller configured toexecute, based on the vehicle peripheral information, following-travelinter-vehicle-distance control of causing the own vehicle to follow apreceding vehicle traveling immediately ahead of the own vehicle whilemaintaining an inter-vehicle distance between the own vehicle and thepreceding vehicle at a predetermined distance, and to execute automaticstart control of causing the own vehicle to automatically start when thepreceding vehicle starts after the own vehicle has been stopped by thefollowing-travel inter-vehicle-distance control in response to stoppingof the preceding vehicle; a notification device configured to issue to adriver a notification for inquiring whether the driver desires theautomatic start control to be executed; and an operation device to beoperated by the driver in order to perform a predetermined responseoperation in response to the notification, the vehicle controller beingconfigured to set an operation mode of the automatic start control toany one of a first mode, in which the automatic start control isexecuted, and a second mode, in which the automatic start control isinhibited from being executed, the vehicle controller being furtherconfigured to, when the own vehicle has stopped in response to thestopping of the preceding vehicle during execution of thefollowing-travel inter-vehicle-distance control and when the operationmode is set to the second mode: determine, based on the vehicleperipheral information, whether a current travel state of the ownvehicle is a specific state, in which there is a high probability thatthe driver desires the automatic start control to be executed; cause thenotification device to issue the notification when it is determined thatthe travel state is the specific state; set the operation mode to thefirst mode when the driver has performed the response operation; and setthe operation mode to the second mode when the driver has not performedthe response operation.
 2. The vehicle travel control apparatusaccording to claim 1, wherein the vehicle controller is configured to,when the operation mode is set to the first mode: maintain the operationmode in the first mode until a predetermined finish condition issatisfied; and change the operation mode from the first mode to thesecond mode when the predetermined finish condition is satisfied.
 3. Thevehicle travel control apparatus according to claim 1, wherein theinformation acquisition device is configured to further acquire, as thevehicle peripheral information, road information, which is informationon a type of a road on which the own vehicle is traveling, and whereinthe vehicle controller is configured to: determine, based on the vehicleperipheral information, whether a first specific state condition issatisfied, the first specific state condition being satisfied when theown vehicle is traveling on a limited-access road; and determine, whenit is determined that at least the first specific state condition issatisfied, that the travel state is the specific state.
 4. The vehicletravel control apparatus according to claim 3, wherein the vehiclecontroller is configured to: determine, based on the vehicle peripheralinformation, whether a traffic-congestion condition is satisfied, thetraffic-congestion condition being satisfied when the own vehicle istraveling in a traffic-congestion section; and determine, when it isdetermined that the traffic-congestion condition is satisfied inaddition to the first specific state condition, that the travel state isthe specific state.
 5. The vehicle travel control apparatus according toclaim 1, wherein the information acquisition device is configured tofurther acquire, as the vehicle peripheral information, roadinformation, which is information on a type of a road on which the ownvehicle is traveling, and wherein the vehicle controller is configuredto: determine, based on the vehicle peripheral information, whether asecond specific state condition is satisfied, the second specific statecondition being satisfied when the own vehicle is traveling on a generalroad and a predetermined moving object does not exist around the ownvehicle; and determine, when it is determined that at least the secondspecific state condition is satisfied, that the travel state is thespecific state.
 6. The vehicle travel control apparatus according toclaim 5, wherein the vehicle controller is configured to: determine,based on the vehicle peripheral information, whether atraffic-congestion condition is satisfied, the traffic-congestioncondition being satisfied when the own vehicle is traveling in atraffic-congestion section; and determine, when it is determined thatthe traffic-congestion condition is satisfied in addition to the secondspecific state condition, that the travel state is the specific state.